Examining the events in the last two decades, it seems strange that so many school-shooting occurred in recent years. 
Thus, I would tell people the current technologies in surveillance station/system.  According to inside information from Taiwan, the invisibility technology has been developed successfully in WWII by US Navy.  After using invisibility technology on the personnel and their equipment, they will become invisible, tiny and have the characteristic of levitation (floating in the air as weightless condition). Thus, the invisibility technology cannot be used in military and has been changed to use in surveillance system.  In 1950s, this invisibility technology has been transferred to Taiwan's surveillance system.  Based on the characteristic of levitation of invisibility technology and using propulsion equipment, every invisible operative can move as a single-seated "plane" (with carried equipments such as weapons & mind machine).   Thus, the invisible operatives can lightly fly onto people's head to control people's brain functions without targets' knowledge. Also, they can lightly land on a target's body (on any organ) to induce illness/death without most victims' knowledge.  Since 1960s, the Taiwan's invisible operatives of surveillance station/system have secretly enter important political persons' homes/offices, cars, etc. to keep them under close surveillance and secretly induce illness/death on some victims whom Chiang Ching-Kuo disliked.    These invisible operatives' codename was "little spirits" in 1965-70 when US defense started the classified research (Operation Pandora) on illness/death inducing techniques.  They have changed the codename from "little spirits" to "bees" to prevent their secret from knowing by others.  That's because most westerners know that "little spirits" in Pandora box are invisible, tiny and would spread illness/death on man (please see details on my webpage Part II-A, C1, C2 and Part I-A3).

The above situation in surveillance system must be same in US.  Thus, after mind control technology has been used in the US surveillance system, the invisible operatives can also secretly fly onto people's head to manipulate people's emotion, behaviors and bodily functions.   Thus, it has become an emotional and behavioral control system.  Unfortunately, some involved LEO also secretly & illegally transferred illnesses/death inducing techniques for use in the surveillance system. Therefore, the current US surveillance system has been illegally altered to be a life control surveillance system, and the involved LEO of surveillance station/system have become the life controllers of local citizens (please see Part I-B and C for details).   This means that the involved LEO & operatives of surveillance system can use invisibility technology to become invisible and tiny to achieve four goals.

1. Spying on anyone without any privacy:  The invisible operatives can secretly enter people's home/office, car, boat, plane, etc. to keep people under close surveillance.

2.  To manipulate people's emotional states and behavior control: After they enter people's home/office, car, boat, plane, etc., the invisible operatives can further fly onto people's head to manipulate citizens' emotions, behaviors with brain map knowledge & remote electric method (see details on my webpage Part I-B).

3. To criminally drive unaware victim mad and/or to kill with microwave voice device: 
After the invisible operatives secretly fly onto a target's head, they can use mind control technology and equipment (microwave voice device-see details on my webpage Part I-A2) to drive unaware victim mad and /or to kill.

How could the invisible operatives secretly communicate with an unaware victim at his home?

After secretly enter a target's home, the invisible operatives mostly will use their characteristic of levitation (floating in the air as weightless condition) to stay around the upper section of wall. From the wall, some of invisible operatives will use microwave voice device to deliver their questions or instruction to the victim.  Also, an operative will secretly fly onto a target's head and also use mind machine (or advanced mind reading technique) to know the target's mind (then know the target's answer).  At the same time, the invisible operative (who fly onto the victim's head) will then loudly read the target's mind (answer) with microwave voice to notify other invisible operatives.  Thus, the invisible operatives can use microwave voice device to communicate with an unaware target (see details on Part I-A2).  However, these invisible operatives can also set up the unaware victim without victim's knowledge (e.g. pretend to be demons to mislead the victim).

4. To criminally induce illness/death on some citizens whom the involved LEO dislike: The invisible operatives can use illness/death inducing techniques to criminally induce illness/death on any citizen whom the involved LEO & invisible operatives of surveillance system dislike.

The following information proves that the first aim of mind control research is to develop their invisible operatives to become professional assassins. After the microwave voice device and EM mind machine have been invented in 1973, the invisible operatives also started to use above equipment to mind control their target to become an assassin/murderer (drive the victim to kill other).

(Attachment 1) "Some Aspects of Anti-Personnel Electromagnetic Weapons" By David G. Guyatt (david.g7@ukonline.co.uk) 
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It was not until the middle or late 1970's that the American public became aware of a series of hitherto secret programs that had been conducted over the preceding two decades by the military and intelligence community. (3) Primarily focusing on narco-hypnosis, these extensive covert programs bore the project titles MKULTRA, MKDELTA, MKNAOMI, MKSEARCH (MK being understood to stand for Mind control), BLUEBIRD